914 On Aquatic Carnivorous Coleoptera or Dytiscide. 
qd ip y 
by two rather elongate straight claws, which are closely applied to one another, 
immobile, and subequal in length: when the outer face of the tarsus is carefully 
examined it is seen to display a peculiar sculpture, consisting of coarse shallow 
punctures, each of which bears a very adpressed elongate squama or scale, at the 
hind margin of each joint these squamze are contiguous to one another, and form a 
series of ciliz overlapping the following joint. The front and middle legs are 
slender and densely ciliate with very long hairs. Epipleuree of elytra very reduced, 
and not fitting closely to the margins of the body, except just at the shoulder, with- 
out the least elevated line on their inner face. ‘The basal ventral segment shows 
at the side an elevated margin which is a little curved, and there is left between it 
and the epipleura a considerable gap or opening: the epipleura is here at its narrow- 
est, and behind this opening again becomes slightly broader; the upper edge of the 
epipleura is set, as it passes the third, fourth, and fifth ventral segments, with short, 
rigid spines. The side pieces of the ventral segments are greatly reduced, that of 
the first is peculiar ; it is bounded below by the curved raised line above described, 
and this line in front is dilated and flattened out so as to form there a flat piece 
which articulates directly with the hind border of the metathoracic epimeron ; 
except for this anterior portion the rest of the side piece is almost membranous; the 
side piece of the second segment is still more membranous, and on the following 
segments the side piece may be said to be reduced to an almost linear piece. 
The apical stigmata are peculiarly small. 
The male front tarsi are highly d2veloped ; the three basal joints are dilated and 
coadapted to form a circular plate, which beneath is fringed with cilize, and bears at 
the base two large cups, and on the rest of the surface dense glandular pubescence, 
each hair of which is in fact a stalk, bearing a minute palette at its apex; the 
middle tarsi are undilated ; the females are without peculiar sexual sculpture, but 
in one of the two species, they have a short impression near the lateral margin of 
the wing-case about the middle. 
This genus is certainly one of the most interesting of the Dytiscide, and its 
detailed study will probably be attended with interesting results. The following 
points are worthy of attention. First, the reduced wing-cases, colour, and soft 
skeleton ; these should be compared with certain Ceelambi, (vide Hydroporus ennea- 
grammus, No. 419) where we find a parallel condition. Second, the serrate edges 
of the elytra are peculiar. Third, the direct articulation between the basal ventral 
sidepiece and the metathoracic epimeron. Fourth, the peculiar sculptured hind 
tarsi. Fifth, the development of the hind coxe, and the ciliation of front and 
middle legs, carried to a greater extent than in any other water-beetle ; and, sixth, 
the beautiful development of a band of transverse pubescence on the upper face 
of the hind femur. 
This combination of points of peculiar interest indicates a very isolated ancestral 
record, and peculiar habits. 
